Protective device



Dec. 25, 1945. WADE HAL 2,3917% PROTECTIVE DEVICE Filed May 9, 1942 2Sheets-Sheet l F'I J.

ITIVET'YCOYS'. Elmer J.\/\/ade, Joseph Horvatl'hJr; by W 6. JMM} TheirAttorney.

2 Sheets-Sheet 2 Fig.4.

n m w m fiw n rJ er A veH Tmw 5w J Dec. 25, 1945. E. .1. WADE ET ALPROTECTIVE DEVICE Filed May 9, 1942 Patented Deals 1945 rnorrzc'rrvanavrcn Elmer J. Wade and Joseph Horvath, In, Pittsfield, Masa, assignorato General Electric Company, a corporation of New York Application May9, 1942, Serial No. 442,338

13 Claims.

Our invention relates to protective and circuit interrupting devices,and has application to overvoltage protective devices such as lightningarresters, and to fuse devices and electric circult interrupters.

An object of our invention is to provide an improved protective devicewhich is efllcient and reliable in operation and which has a relativelylong life.

Another object of our invention is to provide an improved protectivedevice which is efflcient in operation over a relatively wide rangecircuit conditions.

A further object of our invention is to provide an improved overvoltageprotective arrangement which has a relatively rapid insulation recoverycharacteristic.

A still further 1 object of our invention is to provide an improvedcircuit interrupting device which is efiicient and reliable inoperation, and which has a relatively long life in service.

Further objects and advantages of our invenorder to provide an arc paththe concentric cylinders have openings adjacent the electrodes. Theseopenings may be staggered in any suitable direction, such' as an axialdirection so as to provide a circuitous or zig zag arc path between eachaxially disposed electrode and the adjacent end of the tubular member.The pair of gaps may be serially connected across an apparatus in anysuitable manner such as by connecting, one of the axial electrodes to asuitable apparatus to be protected and the other tion will becomeapparent from the following description referring to the accompanyingdrawings, and the features of novelty which characterize our inventionwill be pointed out with particularity in the claims annexed to andforming a part of this specification.

Fig. 1 is a sectional side elevation of an overvoltage protective devicewhich is provided with an embodiment of our invention; Fig. 2 is anexploded perspective view of a portion of the protective deviceillustrated in Fig. 1; Fig. 3 is a sectional side elevation of amodification of the device illustrated in Fig. 1, and Fig. 4 is asectional side elevation of a modification of the over-voltageprotective devices illustrated in Figs. 1, 2, and 3.

In the arrangements illustrated in the drawings, we have shown ourinvention as applied to an overvoltage protective device which will passhigh current impulses such as those caused by. switching impulses orlightning discharges, but it is to be understood that our invention hasapplication to any other suitable protective device .or circuitinterrupting device which may provide a path for surges of shortduration, or such devices as may be called upon to interrupt a powerfollow current, or interrupt an electric circuit. One of the illustratedembodiments of our invention includes a pair of axially disposedelectrodes and a tubular arrangement radially spaced from the axialelectrodes and having electrode portions at either ends thereofproviding radial arc gaps with the adjacent ends of the axially disposedelectrodes. A plurality of spaced barriers or radially spaced concentriccylinders are provided between each of the axially disposed electrodesand the adjacent electrode portion of the cylindrical member. In

portions 55 and I6 providing the electrodes.

one to ground. One of the ends of the concentric ,cylinders may beclosed by a cap member, the opposite end being open so that gases formedby an arc passing between the adjacent electrodes may flow axiallythrough the spaces between the concentric conductors and acros the are,thus extinguishing it.

Referring more particularly to Fig. 1 of the drawings, we haveillustrated an overvoltage protective device iii which may be placed inany suitable housing ll of insulating material. The protective deviceincludes a pair of axially disposed electrodes l2 and 93 which may haveany suitable shape such as a rod shape. To cooperate with the electrodesl2 and 63 we provide a suitable electrode arrangement, and in thestructure illustrated in Fig. i this includes a tubular arrangement Mhaving an electrode portion H5 at one end and an electrode portion l5 atthe opposite end. Since these portions l5 and i8 are adjacent to butspaced from the electrodes l2 and i3, respectively, it will be seen thatthe electrodes l2 and i5 form one gap and the electrodes l3 and i6 form.a second gap. These gaps may be connected in series in any suitablemanner such as by forming the tubular arrangement H of a conductingmaterial with A discontinuity, however, is provided in the tubulararrangement l4 for reasons which will be brought out below. A tubularmember ll of suitable insulating material surrounds the tubular memberI4, and the end members or caps l8 and I9 relatively rigidly support thetubular member H intermediate the ends of the insulating member I! byspacers 20. The electrode assembly including the pair of gaps may beconnected across any suitable circuit or apparatus, and in thearrangement illustrated in the drawing the electrode I2 is adapted to beconnected to a transmission line throu a conducting member 2| which iselectrically connected to the opposite end of the rod which forms theelectrode I 2 by means of a nut 22; An insulator 23 is supported on topof the conducting member 2|, and the upper end of the insulator 23supports a conducting member 24 which may be attached to thetransmission line through a conductor 25. A conventional gap 23 isprovided between the adjacent portions of ground through a conductor 21.The cap member 13 has an integral central portion 23 which supports theelectrode l3, and another integral portion 28 of the cap I3 iselectrically connected to the conductor 21 through a connector 30. Whena high voltage surge occurs on the transmission line to which theelectrode l2 is connected .the gap 26 will spark over and an arc will beformed between the electrodes l2 and 3. the electrode l3 and formanother are between it and the cooperating electrode l3. The surge maythen pass through the electrode l3 and the conductor 21 to ground.

Between the gaps provided by the electrodes I 2 and I and the electrodesI 3 and it we have provided a plurality of radially spaced concentriccylinders 3| which, in the arrangement illustrated in Fig. 1.v arecoaxial with the axiallyspaced electrodes l2 and I3. Any suitable numberof cylinders 3| may be provided, and in Fig. 1 three are shown. Thesecylinders are supported through an insulating member 32 which spans thespace between the electrodes i2 and I 3. Plus 33 of suitable insulatingmaterial passthrough the member 32 and cooperating apertures in thecylinders 3| so as to support them in proper spaced relationship. Aswill be seen in Figs. 1 and 2 these insulating cylinders 3| are ofdifl'erent lengths and the opposite ends thereof cooperate withconcentric insulating cylinders 34 and 35, these latter cylinders beingsupported in proper spaced relationship by means of a plurality of pins33 which are supported by the electrodes l2 and I3 and which passthrough cooperating apertures in the cylinders. Openings or slots 31 areformed between the ends of the cylinders 3i .and the adjacent ends ofthe cylinders 34 and 33 which are not in contact. These slots define arcpaths through which an arc may pass between the cooperating electrodes12 and I5, and I3 and It. By properly dimensioning the cylinders ll, 34,and 35, the openings 31, as will be seen in Fig. 1, are staggered so asto provide a zig zag or circuitous arc path between the electrodes l2and i5, and I3 and I8. Instead of axially staggering the openings 31, itis to be understood that the openings may take any other Furthersuitablerelationship to each other. more, instead of forming the passages 31 by00- operating ends of separate cylinders a single integral cylinder maybe employed which merely has openings or slots therein, as isiliustratedin Fig. 3.

When a sufliciently high voltage is impressed across the electrodes i2and i3, it will be seen that a pair of arcs will be formed between thecooperating electrodes 62 and i5, and i3 and it. In order to enhance therate at which gaseswill be formed when an arc takes place, the cylinders3|, 3%. and 35 may be made of insulating material such as hard fiberwhich has the property 01- giving off deionizing or un-ionized gases.

when heated. Let us assume that a high voltage surge of short durationcauses the gaps formed by the electrodes to arc over. The power followcurrent will then continue to cause an arc to be formed in the gaps andduring increasing values of the power follow current cycle, gases of athe deionizing type will be formed at an increas-- ing rate. These caseswill flow in both directions and in flowing upwardly towards the end capit The electrical impulse will then pass to a pressure will bedevelopedflin the spaces, be tween the radially spaced concentriccylinders.-

Then as the power follow current cycle apders will be open to theatmosphere. The pressure thus developed at the end of the tube adjacentthe enclosing cap l8 will cause the gases to be blown downwardly towardthe vent openings 38. Since the arc paths between the cooperatingelectrodes l2-and l5, and I3 and it are relatively far apart the gaseswill become cooled and deionized as they pass between the concentrictubes towards the vent openings 38. Furthermore, the gases formed by theupper arc will contribute to the production of the pressure toextinguish or blowout the are formed between the electrodes l3 and id asthe power follow current passes through zero and the recoveryvoltage isimmediately impressed acrossthe protective device. By blowing the gasesover the cylindrical or peripheral surfaces of the concentric tubes andby pacing the parallel disposed gaps a relatively great distance apartand further by providing a zig zag arc path between the electrodes,

we have found that the resulting protective device has a relatively highinsulation recovery strength. v

In order to further improve the operating characteristics of the device,a coil 40 may be provided with opposite ends electrically con-v nectedto the electrode portions l5 and I6, re-

. spectively. The conducting tubular arrangement I4 is provided with aradial discontinuity II, or the portions of tubular arrangement l4having electrode portions l5 and ii ar spaced apart so as to provide agap in parallel with the coil 40 whereby the power follow current willtraverse the coil and cause the arcs between the cooperating electrodesto rotate. This gap shunting the coil also helps to prevent impulsecurrents from flowingthrough the 'coil. Movement or rotation of the archelps to prevent localized burning and to cool the are at low currentsand it will cause the are to pass over a relatively large portion 01'the gas evolving material thus contributing to a relatively rapid rateof evolution of deionizing gas. Furthermore the staggering of the gapsor slots in the concentric cylinders contributes to the relatively highinsulation recovery characteristics which we have found-our devicepossesses. The idea of coupling a coil with one electrode to rotate thepower arc is described in further detail and claimed in application S.N.- 442,337,- Wade, filed concurrently with the present application andassigned to the same assignee as this present invention.

Referring to Fig. 3 of the drawings, we have illustrated a modificationof our improved protectivedevice which includes an electrode, 50 which isupported by a pair of insulating columns 5i and 52. We have provided aplurality of concentric cylinders 53 which are coaxial with thelongitudinal axis of the center electrode Ell. An electrode arrangementis provided on the outside of the cylinders 53 including electrodes 56and 55. These electrodes are placed on opnumber of openings 88 which maybe staggered so as to provide an arc path between the electrode Ill andan electrode portion 51 oi the electrode 50. Similar openings 58 areprovided between the electrode 55 and the electrode portion 59-01 theelectrode member 50. The electrode 54 may be supported and electricallyconnected to an end cap 80 while the electrode 56 may be in turnsupported by an opposite end cap H.

The end cap Si is rovided with vent openings iii which communicate withthe spaces between the concentric cylinders, while the end cap 60provides an enclosing member so as to provide a space 63 between theends of the concentric cylinders lit and the end cap 60. The end caps 60and bi may, therefore, be connected across the apparatus which is to beprotected, and when a suflicient voltage is impressed across theprotective device an arc will be formed between th electrodes d and 51through the openings 56 and between the electrodes 59 and 55 through theopenings 58. The concentric cylinders may be composed of any suitablemateriel such as one having the property of giving oh the deionizing orun-ionized gases when heated, and during increasing values of powerfollow current a pressure will be developed in the reservoir 83, whichduring decreasing values of power i'ollow current, will cause the gasesto move outwardly through the vent passages 52. The gases flow acrossthe arc path and introduc gas of a relatively high dielectric strengthinto the arc stream by turbulent iiow which contributes to the rapidrecovery insulation strength at the current zero.

In Fig. 4 we have illustrated a further modification oi our protectivedevice including an up per electrode lill which may be connected to aline or apparatus to be protected, and a lower electrode ii which may beconnected to ground through the conductor l2. A pair of gaps areprovided between the electrode Ill and an adiaccnt electrode is which isradially spaced therefrom. Anothergap is provided between an electrodeit and the center electrode ill. The electrodes it and it may be of anysuitable construction and in the arrangement illustrated in Fig.

' 4 they include opposit ends oi a spaced wound coil l5. An arc path isprovided between the electrodes it and i3 by insulating disks l6 and ii.The coil it is carried by an insulating housing 18 and is spaced thereinbetween a shoulder l9 and a cylinder til. enclosed at one end by a metalcap 8i and the other end is enclosed by a metal cap 82 having ventopenings 83. The insulating disk 16 is spaced from the inner walls ofthe insulating cylinder at providing a passage 84 which leads to areservoir 85. The are path between the electrodes II and 14 is providedby an insulating circular plate 86 and a plurality of concentriccylinders 8! which are supported at their lower ends by an insulatingmember 88. Teeth 89- are provided at the opposite endof the cylinders81, which teeth extend into cooperating slots in the plate 88. Ventopenings 98 are provided in the disk 88, which openings communicate withth spaces between the concentric cylinders 81. The outer edge of theinsulating plates 11 and 85 are spaced fromth'e inner surface of thecoil 15 so as to provide a passage M which communicates with the arcspaces between the electrodes l0 and It, and 'H and 14.

When a voltag of suihcient magnitude i 'impressed across the electrodesand Ii, arcs will be formed in the gaps provided between the The housingis tightly electrodes I8 and I8, and II and II. In order to enhance thequantity 01' gas which is given out due to the heat of the arc theinsulating plates I8, Ti, and 88, and th concentric cylinpower followcurrent cycle, gases will be formed by the upper gap. mrt of which willflow into the reservoir 85. As the power follow current decreases andapproaches zero the pressure in the chamber 85 will be greater than atthe open end thereof so that the gases will flow across the upper gap,down the peripheral or cylindrical passage 9! and across the are betweenthe electrodes 'iiand i4, thus providing for a relatively rapidinsulation recovery characteristic of the protective device.

Since the electrode id is in the form of a spaced wound coil, the powerfollow current will flow through the turns or the coil and cause thearcs to rotate. Since the coil has gaps impulse currents will jump thgaps between each turn instead of flowing around the coil. A plug d2 ofsuitable magneticmaterial such as iron may be provided between theinsulating plates ii and 86 for enhancing the electromagnetic forceavail able tor rotating the arc.

Although we have shown and described par ticular embodiments of ourinvention, we do not desire to be limited to the part cular embodimentsdescribed, and we intend in the appended claims to cover allmodifications which do not depart from the spirit and scope of ourinvention. 1 What we claim as new and desire to secure by Letters Patentin the United States is:

l. A protective device including a substantially rod-shaped metalelectrode, a second metal electrode having a tubular shape spaced fromand surrounding said first electrode to form a gap, and a plurality ofsubstantially concentric insulating radially spaced cylinders betweensaid electrodes, said cylinders formed of an insulating material whichgives 0E an arc-extinguishing gas when subjected to the heat of anelectric arc, said cylinders having staggered openings dem a circuitousarc path through which an arc may strike between said electrodes.

2. A protective device including a tubular shaped electrode, a rodshaped electrode concentric with said tubular electrode and having aportion within said tubular electrode, and a plurality of radiallyspaced substantially concentric insulating cylinders between saidelectrodes formed oi a material which gives off a gas when subjected tothe heat of an electric are, said cylinders having openings axiallystaggered defining a circuitous arc path through which an arc may strikebetween said electrodes.

3. A protective device including a plurality of radially spacedsubstantially concentric insulating cylinders, first electrode meansinside said cylinders and second electrod means outside said cylindersdefining two spaced arc gaps, said cylinders having at least two groupsof openings defining at least two radially extending arc paths betweensaid first and said second electrode means, and mcansfor enclosing theadjacent ends of one end of said cylinders the opposite end of saidcylinders being substantially unobstructed so that gases formed due toarcs may flow from the enclosed end of said cylinders between saidcylinders and across the arcs between said gaps.

one endof said cylinders th other end thereof flow from said enclosedend through the spec 7 aeerfr se mentioned electrodes and said tubularmeans electrode portions, said insulating cylinders having openingsadjacent said electrodes providing between said cylinders across th arcand out the open end of said cylinders.

5. A protective device including a plurality of radially spacedsubstantially concentric insulating cylinders of a type which give oil agas when subjected to the heat of an electric arc, a solid electrodehaving .a, portion within said cylinders, a tubular electrodesurrounding said cylinders, said cylinders having substantially radiallyextending openings defining an arc path between said electrodes, andmeans for enclosing one end of said cylinders the other end thereofbeing open so that gases evolved from said cylinders during arcingbetween said electrodes may flow from said enclosedend through thespaces between said cylinders across the arc and out the open end ofsaid cylinders.

6. A protective device including a pair of axially spaced electrodes,tubular means radially.

spaced from said first-mentioned electrodes and having electrodeportions at each end providing arc gaps with the adjacent of saidfirst-mentionedelectrodes, and a plurality of substantially concentricinsulating cylinders between said firstmentioned electrodes and saidtubular means electrode portions, said insulating cylinders havingopenings adjacent said electrodes providinga pair of arc paths for thearc gaps.

'Z. A protective device including a pair of axially spaced electrodes,tubular means radially I spaced from said first-mentioned electrodes andhaving electrode portions at each end providing arc gap with theadjacent of said first-mentioned electrodes, a plurality ofsubstantially concentric insulating cylinders between saidfirstmentioned electrodes and said tubular means electrode portions,said insulating cylinders having openings adjacent said electrodesproviding a pair of arc paths for the arc gaps, and means for enclosingone end of said cylinders so that gas formed by the arc of one gap willflow between said cylinders and across the arc of the other gap.

8. A protective device including a pair of aid-- ally spaced electrodes,tubular means radially spaced from saidfirst-mentioned electrodes andhaving electrode portions at each end providing arc gaps with theadjacent of said first-mentioned electrodes, and a plurality ofsubstantially concentric insulating cylinders between saidfirst-mentioned electrodes and said tubular means electrode portions,said insulating cylinders having openings adjacent said electrodesproviding a pair of arc paths for the arc gaps,

and coil means for providing a field to rotatethe arcs in said arepaths.

9. A protective device including a pair of axially spaced electrodes,tubular means radially spaced from said first-mentioned electrodes andhaving electrode portions at each end, providing arcgaps with theadjacent of said first-mentioned electrode, a plurality of substantiallyconcentric insulating cylinders between said firstelectrode portions sothat the power follow cur-- rent will fiow through said coil and rotatethe arcs in said are paths.

10. A protective device including a p ir of am-' ally spaced electrodes,tubular means radially spaced from said first-mentioned electrodes andhaving electrode portions at each end providing arc gaps with theadjacent of said first-mentioned electrodes, a plurality ofsubstantially concentric insulating cylinders between saidfirstmentioned electrodes and said tubular means electrode portions,said insulating cylinders hav= ing openings adjacentsaid electrodesproviding a pair of arc paths for the arc gaps, means for connecting oneof said axially spaced electrodes to an electrical apparatus to beprotected and the other of said axially spaced electrodes to ground, anelectrical coil surrounding said tubular means and having ends connectedto said electrode portions so that the power follow current will flowthrough said coil and rotate the arcs in said are paths, said tubularmeans having a. discontinuity to provide a gap in shunt with said coil.

.11. A protective device including a solid electrode, substantiallyconcentricinsulating cylinders radially spaced and coaxial with an axisof said electrode, said cylinders being formed of a material whichevolves an arc-extinguishing gas when subjected to th heat of anelectric of radially spaced substantially concentric'cyl- 1 indersformed of gas evolving insulating material, electrode means forming aplurality of arc gaps, said cylinders having at least one group ofopenings defining at least one radially ex--' tending arc path for oneor said are gaps, and means for enclosing the adjacent ends of one endof said cylinders the opposite end of said cylinders being substantiallyunobstructed so that gases evolved from said cylinders when arcs areformed across said gaps may flow from the enclosed end of said cylindersbetween said cylinders and across the arc in said are path formed bysaid cylinder openings.

13. A protective device-including a pair of axially spaced electrodes,electrod means radially spaced from said first-mentioned electrodes andhaving electrode portions providing arc gaps with the adjacent of saidfirst-mentioned electrodes, plate means defining an arc path for one ofsaid arc gaps, a plurality of substantially concentric insulatingcylinders having openings providing an arc path for another of said aregaps,

' means providing a passage communicating with said are paths, meansproviding a reservoir communicating with said one of said are gaps andsaid passage, and a vent means communicating with said other of said arcgaps.

ELMER J. WADE. JOSEPH HORVATH, JR.

